1. Field of the Invention
The present invention relates to a semiconductor device including an Si (silicon) microphone or other MEMS (Micro Electro Mechanical Systems) sensor.
2. Description of Related Art
Due to Si microphones manufactured by an MEMS technique being recently equipped in cell phones in place of ECMs (Electret Condenser Microphones), Si microphones are rapidly drawing increasing attention.
An Si microphone has a structure where, for example, an opening is formed at a central portion of a silicon substrate, a diaphragm is disposed opposite to the opening on a top surface of the silicon substrate, and a back plate is disposed opposite to and spaced apart from the diaphragm by a minute interval. When a sound pressure (sound wave) is input, the diaphragm vibrates. When the diaphragm vibrates in a state where a voltage is applied between the diaphragm and the back plate, a capacitance of a capacitor formed by the diaphragm and the back plate changes, and a variation of voltage between the diaphragm and the back plate resulting from the change of capacitance is output as an audio output signal.
It is said that the Si microphone having such a structure can be integrated in a single chip with a chip equipped with a signal processing circuit or other integrated circuit. However, single chip integration of an Si microphone and an integrated circuit chip has not been realized as of yet, and an Si microphone and an integrated circuit chip are provided individually as separate parts.